Aero data from 19 wheels by Hambini

[Matt28NJ]

By end of the day, my vote goes to Reynold ATR 700 but it's disc only You could achieve maximum aero gain with 28mm tire or wider https://reynoldscycling.com/collections ... ts/atr-700

I wonder if a 28mm Conti GP4k on that rim would fit in the new Specialized Allez Disc?

I race a zillion crits every year on absolutely garbage pavement, and I genuinely wonder if a massive 28mm tire, measuring to probably 31mm, would give huge traction advantage on such crap surfaces.

[ericoschmitt]

Interesting result of the LB 56 V wheel, wide as it is! And if you consider you can probably run wider than 23 tires on it without a drawback in aero... Something that measures 28 should be good.

[Imaking20]

I'm pretty certain that Tom and a lot of other engineers are active in this thread for the same reason I am. This is some real science! Or it could/might be,,,,

The reason why the tone seemed to get "hostile" from the perspective of the peanut gallerie is because questions weren't getting answered, and there was no supporting data. And then Hambini resorted to ad hominem and it got more absurd. I figure when someone does that they have something to hide, and could even be a total fraud. I no longer believe that, but at the time I'd never heard of him before, so anything was possible.

But, if someone is presenting data derived from a "revolutionary new test protocol" then everyone with a scientific bent is going to want to know the details. Exactly what it is, and why it's better. Bold claims need to be supported with evidence and explanation. There is nothing weird about that. People who can't grasp the technical aspects though, may not understand this.

K

[aeroisnteverything]

Does it though? Bora 50s perform virtually identical to the 56mm deep LightBicycle and also same as the Bontys. Mavics at 45mm are only marginally worse, and still within the margin of error. How do we explain this? Is this is a fluke?

I think it would be good to remember that he is estimating +-2.5% error. A wheel in the middle of the range will have overlapping error bars with nearly every other wheel in the test. F

See the point at the end of my previous post. I think for similar depth wheels only FLO would fall "out" of range of said error bars vs the "best" wheels of comparable depth.

I've been trying to get Hambini to post VAR or STDEV for a few posts now, all to no success. We would all indeed do well to remember that the differences between wheels within 5 watts of each other on that chart are basically not differences at all, and the ordering has a pretty high ("pretty high" sucks, but the best one can do without knowing the N and the VAR) chance of being the result of a random chance.

[hambini]

fall "out" of range of said error bars vs the "best" wheels of comparable depth.

I've been trying to get Hambini to post VAR or STDEV for a few posts now, all to no success. We would all indeed do well to remember that the differences between wheels within 5 watts of each other on that chart are basically not differences at all, and the ordering has a pretty high ("pretty high" sucks, but the best one can do without knowing the N and the VAR) chance of being the result of a random chance.

I'm not trying to dodge the question. My time is finite and I have a day job which isn't testing wheels. Hence to produce that data will take time and it's certainly not top of my priority list.

To answer a few more questions.

- In my opinion, you can't really generate turbulence when the air is coming at it head on because the pressure gradient is favourable and "energized". Once the air gets past the bulge in the tyre, the pressure gradient is adverse and you can generate lots of turbulence here. Generally, the wheels with the wide brake tracks (internal width is almost irrelevant) do quite well.

- There is one caveat to the above statement and that is if you go away from a wind tunnel and into the real world. The front surface of the tyre can generate turbulence if it is made to oscillate slightly, this is usually rider correction from road vibration and generally goes unnoticed.

-Repetition is built into the test, so every point is tested 5 times.

There is no hard and steadfast rule for saying one wheel will do better than the other, it's all of the parameters working together than specifically one versus another. However a wide brake track is advantageous.

Hambini

[Ed72]

Does it though? Bora 50s perform virtually identical to the 56mm deep LightBicycle and also same as the Bontys. Mavics at 45mm are only marginally worse, and still within the margin of error. How do we explain this? Is this is a fluke?

I think it would be good to remember that he is estimating +-2.5% error. A wheel in the middle of the range will have overlapping error bars with nearly every other wheel in the test. F

See the point at the end of my previous post. I think for similar depth wheels only FLO would fall "out" of range of said error bars vs the "best" wheels of comparable depth.

I've been trying to get Hambini to post VAR or STDEV for a few posts now, all to no success. We would all indeed do well to remember that the differences between wheels within 5 watts of each other on that chart are basically not differences at all, and the ordering has a pretty high ("pretty high" sucks, but the best one can do without knowing the N and the VAR) chance of being the result of a random chance.

Doubtful that random chance is playing a big role here. Five replicates. +/- 2.5% measurement error. Evidence would be the Shimano wheel. The differences are not 5 watts at 50km/h and random chance is much less of a factor than you suggest.

[DurianGrey]

Updated with new wheels and weights and the source data, ignore the color coding in the sheet.

[bm0p700f]

I think hambini started off by saying at 30 kmh the good wheels where all as good as each other. So this critism was dealt with 35 pages ago.

"I've been trying to get Hambini to post VAR or STDEV for a few posts now, all to no success. We would all indeed do well to remember that the differences between wheels within 5 watts of each other on that chart are basically not differences at all, and the ordering has a pretty high ("pretty high" sucks, but the best one can do without knowing the N and the VAR) chance of being the result of a random chance".

1W to 5W is pretty much the same in terms of wheel performance. the error on the best power meters is 1% but 2% on many and at 200W thats 2W to 4W. So there you go you can even meassure it in the real world under controlled conditions. The wheels have to be ranked and I dont think anywhere hambini has claimed the ranking proves one wheel is so much better than the other at 30 kph. He has highlighted a wheel that has peformed much worse than it should given its depth when the air flow occilates rather than steady state. Thats a bit different.

[hambini]

^^^I Agree with above^^^

None of the test takes into account the quality of the hubs, stiffness or braking.

[Matt28NJ]

@Hambini... your next step is to design your own rim!

[hambini]

@Hambini... your next step is to design your own rim!

For my 200W FTP, it's not going to matter what I'm on!

hambini

[Matt28NJ]

@Hambini... your next step is to design your own rim!

For my 200W FTP, it's not going to matter what I'm on!

hambini

Fair enough! I think there are some folks who would be curious how you'd design a wheel - like for disc brakes without the need for a brake track, what would the rim profile look like?

For rim brakes, knowing the constraint is frame clearance, where would you land on design for race wheels?

[Marin]

For rim brakes, knowing the constraint is frame clearance, where would you land on design for race wheels?

Since the sidewalls will be roughly parallel, almost any tall disc brake rim will also work for rim brakes.

[Matt28NJ]

Since the sidewalls will be roughly parallel, almost any tall disc brake rim will also work for rim brakes.

Sure, but when you don't have to build an effective braking surface on the rim of the wheel, it really opens up design possibilities for disc aero wheels! Why think like traditional rim brake designers when the rules are much more open with disc rim construction?

[Monkeyfudger]

^I keep seeing this but is it actually true? If we look at MTB rims (fair do’s no aero) all that’s really happened since discs is they’ve got wider.